Revert "added psycopg2==2.5.3"

This reverts commit ecb949f56d3e1d580a84eb08cceaff697c7d3b46.
Revert "update pg8000 to 1.9.10"

This reverts commit 6446b0be42a7209d61b4cb1f1aef7f309d4809ef.
add mapping for 705 in pg8000